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J. 8. WILSON AND W. E. DALBY.

ELECTRIC REGULATING SWITCH FOR USE WITH ORDNANCE AND FOR OTHER PURPOSES.

APPLICATION FILED OCT-16.1918.

l ,3 1 5, 6 1 7 I Patented Sept. 9, 1919.

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J. 8. WILSON AND W. DALBY. ELECTRIC REGUL ATING SWITCH FOR USE WI' I'H ORDNANCE AND FOR OTHER PURPOSES; nrplcmon FILED oer-'16. ms.

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by 3509M 1. S. WILSON AND W. E. DALBY. ELECTRIC REGULATING SWITCH FOR USE WITH ORDNANCE AND FOR OTHER PURPOSES. APPLICATION FILED MT. 16. 1918.

11,315,617. Patented'Sept. 9, 1919.

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I. s. WILSON AND w. E. DAIRY.

ELECTRIC REGULATING SWITCH FOR USE WITH ORDNANCE AND FOR OTHER PURPOSES.

' APPLICATION FILED 001'- I6. 1918.

I 1 ,3 1 5 ,6 1 7 Patented Sept. 9, 1919.

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THE COLUMBIA PLANDGRAPH c0., WASHINGTON, u. c.

UNITED sTATEs PATENT oEEIcE.

JOHN SIGISMUNI) WILSON, or SUTTON, AND winDI'A vrEnNEs DALEY, gee EoNDoN, ENGLAND, ASSIGNORS 0F ONE-THIRD Tosiit w. e. AnMsT3o e WHITWQRTH & COMPANY LIMITED, 0E NEwcAsTLE-UroN-TYNE, NoETHuMBEnLAN'D, ENGLAND.

ELECTRIC REGULATING-SWITGH FOR UsE WITH GED-NANCE AND Eon OTHER PURPOSES.

Specification ofiettersratein.

Patentedse t. 9, 1919.

Application filed October 16, 191's. sera 1vo.e5s,4sv.

To all whom it may concern:

Be it known that we, JOHN S're'IsM-UND WVILsoN, a subject of the King of Great Britain and Ireland, and residing at Widmerpoole, Grove Road, Sutton, in the count of Surrey, England, formerly of 29 Denbigh street, London, S. W. 1, England, and

WVIL IAM ERNEsT DALBY, a subject of the King of Great Britain and Ireland, and residing at The City and Guilds (Engineering) College, Exhibition Road, London, S. V. 7, England, have invented certain new and usefulImprovements in Electric Regulating-Switches for Use with Ordnance and for other Purposes, of which the following is a specification.

In the specification of our application for British Letters Patent No. 9182 of 1916, apparatus for directing artillery firev against moving objects is described in which there is combined with a director as described in our British Letters Patent No. 6801 of 1915 means by which the resistance in the electric circuit can be varied by an observer according to the height of the target, while the resistance is altered automatically according to the angle of sight so that the total resistance in the circuit corresponds inthe particular manner required with the time offiight of the projectile or other quantity related to the line of sight.

In this apparatus the resistance in the rheostat is variable in two ways, firstly, a series 01": contact strips are so arranged that the resistance is varied by the movement of a lineof sightin a second instrument used to follow the target in the vertical plane and secondly, by a device which is set according Y tothe height of the target which isotherwise observed. The resistance in circuit, therefore, depends upon two factors, first,

the inclination of the line of sight to the horizontal, and second, on theheight ofthe target which has been determined by any suitable means. I

In the apparatus according to the said specification, an automatic selector is provided attached to the director and consisting oftwo independent sets of strips mounted on a cylindrical surface wi-thresistances and moving contacts mounted to work together so that one series of-resistancesis in circuit withthe vertical director magneto and its detached indicators [101' srghting elements,

while the other setof strips and resistances is in circuit with the directorused for oby specification some difficulty arises'owing to the fact that the contact strips at certain parts of their length require to be very narrow and close together in order that a sufficient number of resistance steps may be obtained with a small angle of revolution of the cylinden v j The objector the present invention is to provide a variable resistance device in which the strips and contacts are so arranged that a comparatively large number of resistance steps may be obtained with a small angle of revolution of the member carrying the strips. 1

The invention is applicable to many purposes other than the application to directors for directing artillery fire of the type described in our aforesaid specifications.

The invention consists broadly in a rheostat having a rotary or sliding contact de- Vice in which two or more simultaneously adjustable contact arms are provided, with a corresponding number of sets of contact strips on a rotary or sliding member, the strips being connected together in one or more groups by resistances so that a number of alternative circuits are made through "the arms and sets of contact strips at each altered from one step to the next by an angular movement of the rotary or sliding memberless than that corresponding with the width of the contact strips in the vicinity of the contact point.

The invention further consists in a rheostat for use in directing artillery fire as hereinafter described- In carrying the invention into efii'ect, for example, in a case in which the contact device consists of two contact arms a, b, and

the sliding or rotating member carries two sets of strips a a a and b b b corresponding to each of the two contact arms respectively, the sets of strips may be arranged diametrically opposite each other on a disk and the contact arms may be mounted to turn, about centersnear the'circumference of the disk sothattheir contact points swing acros t e di k along circularpaths between the center and the circumference, suitable gearing being provided between the contact arms by which they are moved simultaneously so that the radii from the center of the disk to the two contacts are always equal. Electrical resistance wires are connected between the Contact strips. One terminal is connected to this series of resistances and plates and the two contact arms are connected in parallel to the other terminal.

Referring to the accompanying drawings:

Figures 1, 2, and 3 are diagrams explaining the operation of the invention;

Fig. 4 is a side view partly in section;

Fig. 5 is a transverse section; and

Fig. 6 is a view showing the resistance bobbins and plates of an instrument constructed according to the invention.

In the example illustrated in Figs. 1, 2, and 8, let the contact points a I) be at the periphery of the disk and let the widths of the contact strips or plates (L -66 and 7),5 be such that the divisions between them measured from two diametrically opposite points are as follows, also let the resistance to them respectively from the terminal be as given in the following table Angular distance of divisions between plates from Zero:

Division between plates (4 and a, 10 Division between plates a and a, 20 Division between plates 5 and b 15 Division between plates 5 and b 25 Resistance in circuit between terminal g and plates:

Now, as the disk and plates are turned under the two contacts, up to an angle of 10 as in Fig. 1 the circuit is the same through a and 5 which are in Contact with plates at, and 5 and the resistance is 100 ohms. From 10 to 15 the circuit is made through a or 5, as in Fig. 2, but as the re sistance to a, is 95 ohms and the alternative path is through a loop containing an additional 5 ohms, the contact with a, governs the current. Similarly from. 15 to 20, (0 and 5 are in contact with the arms as in Fig. 3, giving 90 ohms resistance, from 20 to 25 resistance is 85 ohms, and so on, so that the resistance changes from 100 to 95 ohms at 10, 95 to 90 ohms at 15, and from 90 to 85 ohms at 20. The result is that the steps or changes in the resistance occur at intervals of 5 as the disk is turned, whereas the widths of the" contact strips are equivalent to 10.

Similarly with four contact arms and four sets of plates 10 wide, the steps in resistance can be made at every of movement of the disk. The number of groups of plates and contacts can be multiplied to any extent and mounted on several. disks to form one rheostat unit, thus making it possible for steps in the series of resistances to occur with small angular movements of the disks, while the contact strips are comparatively wide. 7 In carrying the invention into effect as applied to the instrument described in our application for British Letters Patent No. 9182 of 1916, as the total angular movement of the cylinder or disk is only 90 we may mount four groups of contact strips on one disk. WVe may also construct the instrument with several disks, each disk being independent of the others so far as electrical connections are concerned, and forming an independent rheostat constructed according to the present invention.

The divisions between the contact plates on these disks would be made to satisfy the ballistic data relating to the gun and ammunition used. The two coordinates to which the required data are referred would be the movement of the contact arms to and from the center of the disks corresponding with the height and the circular motion of the disk to correspond with the angle of sight. The divisions between contiguous contact plates would be shaped to correspond with uniform times of flight, fuse setting numbers or tangent elevation angles or other data referred to, these two coordinates and the resistances connecting the plates would be arranged to produce the required effect on the various currents flowing through the rest of the apparatus.

The disk may be mounted on the same axle and this would be rotated by the attached director or equivalent means so that the axle and any disk attached to it would be set to correspond with the angle of sight of the target. One or more of these disks may, however, be so mounted on the axle that they may be moved so as to be in advance of or behind the other disks or angle of sight so that allowances may be made for the dis tance which will be traveled through by the target during the time taken by the projectile to reach it.

Thus, for instance, with the automatic selector described in our application for British Letters Patent No. 9182 of 1916, the resistance corresponding with the time of flight necessary for regulating the deflection circuit is required to correspond approximately with the observed angle of sight of the target, but the fuse setting number or tangent elevation is required to correspond to the angle of sight the target is expected to be at when the shot reaches it. This anticipated angle of sight is the observed angle of sight with the vertical deflection added or subtracted according to whether the deflection is up or down. The fuse setting number or other data relating to the anticipated angle of sight will therefore be indicated if the corresponding rheostat disk be set in advance of or behind the angle of sight by the vertical deflection angle.

In the form of the invention illustrated in Figs. 4 to 6, room for five disks A, A A A, A, is provided on the axle B of the instrument; these are intended for regulating (respectively the vertical and lateral deflection, tangent elevation, and fuse scale). The fifth disk is for conv'ertingthe lateral measurement if the telescope is moved in azimuth, or other additional adjustment. This axle is placed co-axially with the axle of the vertical director 0 and rotated with the vertical director which is mounted on the pillar (1. Each disk carries on its face four groups of contact strips 6 e e e e mounted on an insulating base, the form of these strips being calculated from the known ballistics of the gun and characteristics of the fuse or other data. The resistances connected to the strips are conveniently wound on bobbins f on the other side of the disk, the whole of the resistances on each plate being placed in series and one end connected to a quadrant contact plate 9 against which bears a contact connected to one of the fixed terminals on the case of the instrument.

Four adjustable contact arms h for each disk are provided having spring contacts is adapted to bear against the contact strips 6 e e e 6 the contact arms being mounted at intervals of 90 on adjustable spindles Z-each spindle carrying five insulated arms h carrying the spring contacts. These four spindles Z are interconnected by toothed gearing m n so that the contact arms traverse their respective groups of plates simultaneously. Each set of four contact arms relating to each plate are connected together and to the second terminal not shown, on the case of the instrument by flexible connections. The setting gearing r s, and setting wheel 0 may operate a suitable pointer 2 moving over a height scale 9 to indicate the height of target for which the contact arms are set.

The fuse setting rheostat and tangent elevation disks a a may be advanced or retarded. rclativelv to the other three disks a, a a, on the line of sight by a suitably graduated dial wheel t operating a pinion u and quadrant -v adapted to turn this disk relatively to the others. This dial is graduated in degrees and set according to the deflection read off from a vertical deflection dial suitably placed. The fuse setting rheostat disk and tangent elevation disk are placed in separate circuits actuating dials on which the fuse setting number and tangent elevation are indicated; or both tangent elevation and vertical deflection may be combined on one dial.

It will be seen that as the disk constructed as above described rotates, the current flows by the contact arm and stri offering the least resistance, with the resu t that the width of the strips may be made greater than would otherwise be the case to obtain the same number ofchanges of resistance for a given angle of rotation of the disk.

It will be seen that although our invention has been described as applicable to directing apparatus as described in our aforesaid applications for British Letters Patent, the device may be applied to a compensator for varying the proportion of current sent through a galvanometer and a shunt respectively without altering the total resistance of the portion of the circuit containing the galvanometer and shunt, or generally in any case where a similar problem of obtaining a number of diflerent resistances with a small relative movement between contacts and resistance strips arises.

Having now described our invention, what we claim as new and desire to secure by Letters Patent is A rheostat comprising in combination a contact device, a number of simultaneously adjustable contact arms carried by said device, a member movable relatively to said contact device, a number of sets of contact strips on said movable member, said number of sets corresponding to said number of contact arms, groups of resistances connecting said strips adapted to make a number of alternative circuits through said contact arms and said strips at each position of said movable member so that the resistance of the rheostat is altered from one step to the next by an angular movement less than that corresponding with the width of the contact strip as set forth.

In testimony whereof we have signed our names to this specification.

JOHN SIGISMUND WILSON. WILLIAM ERNEST DALBY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of .Patents,

Washington, D. C. 

